CENTRALIA STP - Wastewater Treatment Plant in Clinton County, Illinois

CENTRALIA STP is a municipal wastewater treatment plant located in Clinton County, Illinois, serving a population of about 15,738. The facility is part of the region's wastewater infrastructure, treating domestic sewage from the surrounding community. Under the U.S. Clean Water Act, plants of this size are typically required to provide at least secondary treatment to meet National Pollutant Discharge Elimination System (NPDES) permit limits. Regulatory standards ensure effluent quality protects receiving waters. The plant discharges into local waterways that ultimately drain into the Mississippi River basin. This watershed supports diverse aquatic life and provides drinking water for downstream communities. Proper treatment at CENTRALIA STP helps maintain water quality in this ecologically significant river system.

The plant's treated effluent flows into tributaries of the Kaskaskia River, which joins the Mississippi River near Chester, Illinois. The Mississippi River is a major migratory corridor for fish and birds, and its floodplain supports diverse wetland habitats. Protecting water quality in this basin is critical for downstream ecosystems and the Gulf of Mexico, where nutrient pollution can contribute to hypoxic zones.